Problem: $ { \left[\begin{array}{rr}{-2} & {4} \\ {0} & {2} \\ {2} & {-1}\end{array}\right]-\left[\begin{array}{rr}{3} & {-2} \\ {0} & {1} \\ {-1} & {-1}\end{array}\right] = {?} } $
Solution: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{-2}-{3} & {4}-{-2} \\ {0}-{0} & {2}-{1} \\ {2}-{-1} & {-1}-{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-5} & {6} \\ {0} & {1} \\ {3} & {0}\end{array}\right]}$